Pulse Welding Method and Welding Tool for Pulse Welding for a Medical Pack Formed As a Bag

ABSTRACT

The invention relates to a welding tool and a method for pulse welding films of plastic for medical packs formed as bags. The invention generally provides for the film material that has been plastified during welding, and is consequently free-flowing, to be specifically displaced by increasing the sealing surface area. The displaced film material can for instance compensate for dimensional and form tolerances. At the same time, however, the strength of the welded seam region, which adjoins the interior space of the bag, is not reduced.

AREA OF THE INVENTION

The invention relates to a welding tool for pulse welding of plasticfilms for medical packs formed as a bag. Moreover, the invention relatesto a welding method using the welding tool for pulse welding. Theinvention furthermore relates to a medical pack formed as a bag, whichis preferably produced using the method according to the invention.

BACKGROUND OF THE INVENTION

Medical bags consisting of a welded film are known. For example,polyolefin films are used to produce such medical packs.

The published application EP 0 911 141 A2 (Fresenius Medical CareDeutschland GmbH) discloses a device and a method for welding films forthe purpose of producing a medical pack. According to the teaching ofthis document, the welding jaws comprise a heated region and anadjoining cooled region. The welding jaws are pressed onto the filmduring the welding process. Because of the adjoining cooled region, thewelding jaws always rest on a region of non-plasticized film during thiswelding process, so that the welding jaws are held apart from oneanother by the film itself. The material of the weld seam is preventedfrom being displaced to the sides in this manner.

The films thus have essentially the same material thickness in theregion of the weld seams as the total thickness of the adjoining filmslying one on top of another.

Furthermore, welding a port for removing or supplying liquids into theweld seam to produce medical packs formed as bags is known. A port is afitting system for removing or supplying liquids. Such a port can beprovided, for example, by a hose section or by an injection-molded part.Such a port can comprise, for example, a ship-shaped welded-in portionfor this purpose. Such a ship-shaped welded-in portion is disclosed, forexample, in the patent specification EP 1 605 891 B1 (Fresenius KabiDeutschland GmbH).

In particular in the region of the port, high demands are placed on thedimensional accuracy of the parts used for this purpose.

OBJECT OF THE INVENTION

The invention is therefore based on the object of providing a weldingtool and a welding method and also a medical pack produced using awelding method according to the invention, which permit higher shapetolerances of the materials used, but at the same time maintain thepositive pack properties.

SUMMARY OF THE INVENTION

The object of the invention is achieved by a welding tool, a method forwelding a film, and a medical pack formed as a bag according to one ofthe independent claims.

Preferred embodiments of the invention can be inferred from the subjectmatter of the dependent claims, the description, and the drawings.

In general, the invention provides that film material, which isplasticized by heating and is thus free-flowing during welding, isintentionally displaced by an increase of the sealing surface. Thedisplaced film material can compensate for shape and/or dimensionaltolerances. At the same time, however, the thickness of the weld seamregion which adjoins the interior of the bag is not substantiallyreduced.

The invention provides a welding tool for pulse welding a film made ofplastic of a pack, which is preferably medical. The welding toolcomprises a welding jaw having a sealing strip, which extends along thewelding jaw and can be pressed onto the film. The sealing stripcomprises a heatable sealing surface to form a weld seam, in order toplasticize plastic material of the film adjoining the sealing surface.In particular, the sealing strip has an adjoining inner clamping regionand preferably also an adjoining outer clamping region on the peripheryof the sealing surface for clamping the film during welding of the film.Therefore, a cavity is formed in the welding tool in particular duringthe welding. The welding tool is in particular characterized in that thesealing surface has an elevation. The elevation is preferably anelevation for displacing plastic material of the film which is or hasbeen plasticized during the welding procedure.

Plasticized plastic material of the film can be intentionally displacedby the elevation in the sealing surface. The displaced film material cancompensate for shape and/or dimensional tolerances. The plastic materialcan in particular be displaced at least laterally along the weld seam.The elevation can be provided by a profile of the sealing surface. Itcan be provided, for example, by a structure that is convex at least insections or by a type of step.

The elevation in the sealing surface is in particular not capable of ordesigned for severing films inside the weld seam. The elevation in thesealing surface is not and does not have a blade for severing the film.The elevation in the sealing surface is substantially used for theintentional shifting of the plasticized plastic material. The weldingtool is preferably not a welding tool for welding and cutting.

In a first embodiment, the elevation is provided by a plateau, whichprotrudes out of a surface of the sealing surface. The plateau can beembodied level, inclined, and/or curved completely or in sections.

In one embodiment of the invention, the plateau is provided as astrip-shaped contour on the sealing surface. In particular, the plateauoccupies 30% to 80%, preferably 60% to 75%, of the width of the weldseam. In particular, the plateau is provided at a height between 10 and100 μm, preferably between 20 and 60 μm.

In one preferred embodiment, a peripheral inner region of the sealingsurface is arranged depressed in relation to the elevation. The innerregion of the sealing surface is in particular the region of the sealingsurface which produces the peripheral inner region of the weld seam. Theinner region of the weld seam is the region which adjoins the interiorof the bag. A weld seam can thus be produced which has a greaterthickness on its inner side. Such a weld seam is thus embodied so it ismore stable. A filled bag of this type has greater strength uponapplication of pressure.

In particular, a peripheral outer region of the sealing surface can alsobe arranged depressed in relation to the elevation. The outer region ofthe sealing surface is in particular the region of the sealing surfacewhich produces the peripheral outer region of the weld seam. The outerregion of the weld seam is the region which adjoins the exterior or thesurroundings of the bag. A weld seam can thus be produced, which has agreater thickness both on its inner side and also on its outer side andis thus embodied so it is more stable overall.

The plateau can be arranged in the sealing surface, preferablyapproximately centrally. However, it can also be arranged in the outerregion of the sealing surface.

In a further embodiment, the sealing strip has an adjoining innerclamping region and/or an adjoining outer clamping region peripherallyin relation to the sealing surface for clamping the film during weldingof the film. A cavity is thus formed in the welding tool during thewelding.

The inner clamping region and/or the outer clamping region is/arepreferably provided during the welding with a temperature which is lessthan a plasticizing temperature of the film to be welded. The plasticmaterial plasticized in the region of the sealing surface thus cannotflow into the clamping region. A more or less completely closed cavityis thus formed.

In a further embodiment of the invention, the peripheral inner region ofthe sealing surface and/or the peripheral outer region of the sealingsurface is/are located substantially at one height with the respectiveadjoining clamping region. The peripheral weld seam region can thus beproduced having a thickness which substantially corresponds to the filmthickness.

At least a free material flow oriented laterally (along the weld seam)is enabled in particular by the combination of clamping region andprofile (for example, as a plateau) to compensate for manufacturingtolerances of the components (film, port, . . . ), without changing theoriginal film thickness in the transverse direction (transversely inrelation to the weld seam) or producing uncontrolled material expulsion.

The welding tool comprises at least one, preferably two welding jaws,which can be pressed onto a film. One welding jaw or the welding jaws ofthe welding tool, in particular the sealing surface and/or clampingregion thereof, is/are preferably pressed directly onto the films. It isor they are in direct contact with the film to be welded. The twowelding jaws are preferably designed substantially identically. Thewelding tool is thus constructed substantially symmetrically in oneembodiment.

The sealing surface extends over the welding jaw along the longitudinalaxis of the welding jaw. The sealing surface can be heated so as to heatand melt a plastic material of the film to be welded which adjoins thesealing surface.

According to a further embodiment of the invention, the welding toolcomprises a membrane, which bulges upon heating and which at leastcomprises the sealing surface.

Bulging upon heating is understood as bulging of the sealing surface inthe unloaded state, i.e., when it is not held back by a counterforce,which is present, for example, because of the material of the weld seamwhich cannot be displaced.

During a welding procedure, the membrane thus bulges in particular ifmaterial can flow into the weld seam and can compensate in particularfor cavities because of manufacturing-related shape tolerances at thesame time.

The block, which the membrane is preferably part of, is manufacturedaccording to one embodiment of the invention from a material having lowthermal longitudinal expansion, in particular from an iron-nickel alloy.

Preferably, at least the part of the block which comprises the sealingstrip and/or the membrane consists of a material having a coefficient ofthermal longitudinal expansion α at 20-300° C. of less than 10,preferably of less than 5, and particularly preferably of less than2*10⁻⁶/K.

Furthermore, according to one embodiment of the invention, the weldingtool comprises a cooling element, which is cooled in particular usingliquid. An electrical heating conductor is placed on the coolingelement. An upper part having the sealing strip is preferably placed onthe cooling element.

In particular, the cooling element comprises a protrusion, whichprotrudes into the block having the sealing strip and/or the membraneand/or on which the heating conductor is placed. The heating conductoris thus arranged directly adjoining the sealing strip and/or themembrane and is preferably in direct contact with the sealing stripand/or the membrane.

It is obvious that an electrical insulation is to be provided betweenthe heating conductor and the sealing strip and/or the membrane for thispurpose.

In particular, it is provided that the sealing strip and/or themembrane, preferably the entire underside of the block, is provided withan insulating coating, in particular with an electrically insulatingoxide layer and/or ceramic layer, for example, a metal or metalloid, inparticular a silicon oxide layer. The insulating layer preferably has athickness of less than 50 μm, particularly preferably less than 10 μm.It is in particular a layer deposited by means of a plasma method.

In a further embodiment of the invention, the welding tool comprises anupper part having recesses. They are formed to accommodate the welded-inportion, preferably the ship-shaped welded-in portion of the port. Inthis case, the welding tool is designed in such a way that the sealingsurface is hotter and/or can be heated more strongly in the region ofthe welded-in portion than in an adjoining region of the sealingsurface, in which two opposing films are welded to one another.

During operation of the heating conductor, the sealing surface is thusheated more strongly in the region of the welded-in portion of a port,in particular at least temporarily by at least 20° C. Since the weldingjaw and thus the sealing surface are not directly opposing and are onlyopposing by the two films separated from the other sealing surface ofthe opposing welding jaw in the region of the port, in particular in itswelded-in portion, a higher introduction of energy is advantageous inthis region to thus also plasticize the material approximately equallyquickly in this region. A one-step production process is thus enabled.The port can simultaneously also be welded into the weld seam during theproduction of the weld seam.

Various technical solutions are possible in order to achieve this.

According to one embodiment, the heating conductor itself can be taperedin its cross section in the region of the recess, so that it becomeshotter in the region in which the ship-shaped welded-in portion is to bebonded to the film.

According to a further embodiment, the welding jaw, in particular thesealing strip and/or the membrane of the welding jaw, can be formedsomewhat thinner in the region of the recesses for the port, so that animproved heat transfer from the heating conductor to the sealing surfaceis provided here.

According to a further embodiment, the following is provided: To heatthe sealing surface in the port region more strongly, the thickness ofan insulating layer, in particular a silicone layer, via which theheating conductor is connected to a cooling element, is selected to besomewhat greater in this region. The heating conductor is thus cooledmore poorly in the region of the recesses for the port, which results ina higher temperature upon heating.

In a further embodiment of the invention, the sealing surface comprisesat least one protruding ribs, preferably at least two protruding ribs,in the region of a port to be welded in, in particular in the region ofthe ship-shaped welded-in portion for a port.

In particular, ribs are provided which are 0.5-1.5 mm wide and/or whichare 10-60 μm tall. Material is additionally caused to flow in the regionof the ship-shaped welded-in portion of the port by these ribs and thusin particular cavities, for example, because of manufacturing tolerancesof the port, are filled up.

The invention furthermore relates to the use of the above-describedwelding tool for producing a medical pack formed as a bag.

The above-described welding tool can preferably also be used in themethod described hereafter.

In general, the invention also relates to a method for welding a filmmade of plastic. In particular, the invention relates to a pulse weldingmethod for welding the film of a medical pack.

The present invention is also described by a pulse welding method usinga welding tool for pulse welding a film made of plastic of a pack, whichis preferably medical. In particular, the above-described welding toolis used for this purpose in the method. In this case, one welding jaw ofthe welding tool having a heatable sealing surface for forming a weldseam is pressed onto the film in such a way that

-   -   the film is clamped peripherally in relation to the sealing        surface during the welding procedure by a clamping region, which        is cooler than the sealing surface and extends on the periphery        of the sealing surface, and    -   plasticized plastic material of the film is displaced by an        elevation of the sealing strip along the weld seam, preferably        at least laterally, preferably to compensate for shape and/or        dimensional tolerances, wherein the film thickness is maintained        or substantially maintained in a peripheral inner region of the        weld seam. Because the film is clamped peripherally in relation        to the sealing surface during the welding procedure by the        clamping region, which is cooler than the sealing surface and        extends peripherally on the sealing surface, in particular a        cavity is formed in the welding tool during the welding. The        plasticized plastic material of the film can be displaced inside        the cavity formed.

At least a free material flow oriented laterally (along the weld seam)is enabled in particular by the combination of the clamping region andthe contour of the sealing surface to compensate for manufacturingtolerances of the components (film, port, . . . ), without substantiallychanging the original film thickness or producing uncontrolled materialexpulsion in the transverse direction (transversely in relation to theweld seam). In particular, complete welding of all components takesplace as long as the entirety of all tolerance deviations is less thanthe displacement volume of the elevation.

The clamping region is sufficiently cooler or cool that it is providedat a temperature which is less than the plasticizing temperature of thefilm to be welded. In particular, the temperature of the clamping regionis at most approximately 20° C. above room temperature during thewelding.

The film thickness is the thickness of the film(s), at which the film(s)was/were provided. The film thickness in the peripheral inner region ofthe weld seam is maintained, preferably substantially, if it deviates byat most ±10% in relation to the thickness of the film(s) at which thefilm(s) was/were provided.

Preferably, the plasticized plastic material can be displaced by theelevation of the sealing strip not only laterally but rather also into aperipheral inner region of the weld seam and in particular also into aperipheral outer region of the weld seam.

In one embodiment, the elevation of the sealing surface is provided byan elevation in the sealing surface. The elevation is a structuralelevation here, which protrudes out of a surface of the sealing surface.The elevation is preferably provided by a plateau, which protrudes outof a surface of the sealing surface. Further explanations on the plateauand possible embodiments are set forth in the above description and thefollowing description.

In an alternative or additional embodiment, the elevation of the sealingsurface is provided by a bulging membrane, wherein the membranecomprises the sealing surface. Further explanations on the membrane andpossible embodiments are set forth in the following description.

During the welding, a welding jaw having a heatable sealing surface ispressed onto the film, wherein the film is clamped peripherally inrelation to the sealing surface during the welding procedure in aclamping region of the welding jaw.

In one embodiment, at least one welded-in portion of a port is alsowelded into the weld seam, preferably simultaneously. The welded-inportion of the port is preferably provided by a ship-shaped welded-inportion. The welded-in portion can also be provided by a type of tubesection or hose section, however.

During the welding procedure, a force is preferably exerted on the filmby a surface pressure of both the sealing surface and also a clampingregion peripherally adjoining the sealing surface.

The clamping jaw is in particular pressed on sufficiently strongly thatan average force over the sealing surface and the clamping region of0.05 to 5, preferably of 0.1 to 1 N/mm², results at least at thebeginning of the welding procedure.

Due to the clamping of the film in the clamping region, the film is aspacer for the clamping jaws during the welding procedure. In theclamping region, the tool is held apart by the films, so that a closedcavity, which is to be found comparably in an injection-molding process,forms inside the weld seam, for example, between two opposing sealingsurfaces or between the sealing surface and the ship-shaped welded-inportion of the port. This has the result that the plasticized, inparticular molten plastic material is not significantly pressed adjacentto the weld seam.

The sealing surface is firstly heated during a welding procedure, sothat the plastic material adjoining the sealing surface plasticizes toform an integrally-joined bond. The heating is then switched off and, assoon as the plastic material has solidified, the welding jaw is raised.Plasticizing of the plastic material is understood as heating in such away that the plastic at least begins to enter a molten state, so that itcan form an integrally-joined bond.

According to one embodiment of the invention, a higher surface pressureis exerted in the region of the sealing surface than in the clampingregion during the heating of the sealing surface. The displacement orflowing of the plasticized film material can thus be assisted.

According to this embodiment of the invention, surface pressure havingsubstantially equal force per unit of area over both the clamping regionand also the sealing surface is thus not exerted during the weldingprocedure, but rather a higher force per unit of area is exerted in theregion of the sealing surface. The force in the region of the sealingsurface is preferably 1.5 times higher than in the adjoining clampingregion at least temporarily and at least in sections.

In this way, a closed cavity furthermore forms in the region of the weldseam, on the one hand.

At the same time, a pressure builds up inside this closed cavity becauseof the greater surface pressure in a molten material, on the other hand,so that the molten material can flow if a volume is present for thispurpose. Such a volume can be present due to manufacturing-relatedtolerances, for example. Such tolerances can be present in particular onthe outer side of the ship-shaped welded-in portion of a port. They arethus filled up in an improved manner by material of the film to bewelded. A welding method can thus be provided in a simple manner whichpermits higher manufacturing tolerances.

The surface pressure converts due to the liquefaction of the plasticmaterial into a pressure in the cavity, which causes molten material inthe cavities to flow laterally in particular (in the direction of theweld seam length).

Films, for example, can be bonded to one another by the invention.Welded-in portions, for example, ship-shaped welded-in portions, of aport can also be welded between two films, wherein the films enter amolten state and form an integrally-joined bond with the welded-inportion. Possible collapsed points can be filled up in particular by thegreater force per unit of area in the region of the sealing surface,i.e., in the region of the forming weld seam.

The sealing surface is designed in particular as a heatable linear orstrip-shaped surface, which is temporarily heated during a weldingcycle. The heating of the sealing surface can be performed in particularusing a resistance-heated heating conductor.

For welding in the welded-in portion, preferably the ship-shapedwelded-in portion, of a port, the sealing surface can have a recess inaddition to the adjoining clamping region. The shape of the recess isadapted to the shape of the welded-in portion of a port. In oneembodiment of the invention, its shape is adapted to a ship-shapedwelded-in portion tapering to a point at the edges.

According to one embodiment of the invention, the higher force per unitof area in the region of the sealing surface is exerted by a bulgingmembrane, which comprises the sealing surface.

A membrane is understood as a preferably thin-walled section of thewelding jaw, in particular an upper part of the welding jaw.

The membrane is preferably peripherally fixed. As soon as the membraneis heated during a welding cycle, it expands and bulges forward, atleast if no counterforce results, i.e., in the direction of the film,onto which pressure is thus exerted. The membrane preferably rests withits lower side on a heating wire in particular. Bulging is thus onlypossible forward.

The force per unit of area in the region of the sealing surface and thusthe pressure inside the closed cavity in which the weld seam is locatedor formed, can thus be elevated in a simple manner.

The method according to the invention is in particular a pulse weldingmethod. In one embodiment, the cycle time, i.e., the time for placing onthe welding tool, heating the sealing surface, cooling and lifting offthe welding tool, is less than 10, preferably less than 8, andparticularly preferably less than 5 seconds.

The membrane is designed in particular in such a way that it bulges atleast 10 μm, preferably at least 15 μm in the direction of the film inthe unloaded state, i.e., without counterforce due to an applied film.

The membrane is preferably part of the upper part of a welding jaw andis preferably formed in one piece with an adjoining region of the upperpart.

The upper part is preferably formed as a block which comprises themembrane. The membrane is provided in that the block is thinned out inthe region of the membrane.

During a welding procedure, only the sealing surface which is part ofthe membrane, but not the adjoining clamping region, is heated in such away that the film which is in contact is plasticized. Because of this,the block does not expand or at least expands less, so that the membraneis tensioned in the transition region to the block and bulges, since theblock does not follow the expansion of the membrane.

In a further embodiment of the invention, a welding jaw having a sealingsurface is used which has at least one plateau protruding out of asurface of the sealing surface.

The sealing surface, the height of which corresponds peripherally to theheight of the clamping region, thus has a thickened region in the formof a plateau.

The plateau is preferably formed as a plate-shaped contour orprotrusion, which extends centrally, in particular in the middle, alongthe main extension direction of the sealing surface.

The surface pressure in the region of the sealing surface is alsoelevated by the plateau. Furthermore, material which is in the moltenstate can be set into motion by the plateau and fill up possiblecavities in this case.

The plateau preferably occupies 30-80%, particularly preferably 60-75%,of the width of the weld seam. A sufficient amount of molten materialmay thus be moved, without the film thickness being substantiallyreduced in the end region of the weld seam.

In one embodiment, the plateau has a height between 10 and 100 μm,particularly preferably between 20 and 60 μm. The plateau is formed insuch a way that in spite of the plateau, a surface pressure occurs bothover the clamping region and also over the region of the sealing surfaceduring the welding procedure. It is thus also ensured that material isnot transversely shifted (in the direction of the seam width) during thewelding procedure.

In order to bulge sufficiently, but also not to be formed so thin thatthe risk of tearing exists, in one embodiment of the invention, themembrane has a thickness of 100-1500 μm, preferably 300-600 μm.

According to one embodiment of the invention, a multilayered film, inparticular a multilayered polyolefin film, for example, a polypropyleneor polyethylene film is welded. Such multilayer films have improvedproperties with respect to the tear resistance thereof. It has beenshown that in particular also multilayered films can be reliably bondedby the method according to the invention.

The film used for the method preferably has a thickness of 100 to 500μpm, particularly preferably 150 to 300 μm.

Independently of whether a single-layer or multilayered film is used, itis provided according to one embodiment of the invention that the entirefilm is plasticized during the welding method. In particular, all layersof a multilayer film can be plasticized during the welding method. Inthis case, all of the material in the region of the weld seam isconverted into a molten state, wherein a closed volume is produced inthe region of the weld seam by the lateral clamping of the film in theclamping region. Mixing of the layers of the film does not have tooccur. The invention can also relate to the use of a multilayer film,however, which has a thin layer made of a material melting at lowertemperature, which is used as an adhesive layer. In this embodiment, allof the material in the region of the weld seam does not have to beplasticized.

The invention furthermore relates to a medical pack formed as a bag,which can be produced in particular using the above-described method andin particular utilizing the above-described tool.

The bag comprises films welded to one another. According to theinvention, the bag comprises at least one weld seam, which has, at leastin sections, a region thinned out or reduced in the thickness inrelation to an adjoining neighboring region. The neighboring region isprovided by a peripheral inner region of the weld seam. This peripheralinner region of the weld seam is the region of the weld seam whichadjoins the interior of the bag. In the case of a filled bag, thisregion of the weld seam adjoins the liquid contained in the bag, forexample. In this case, the peripheral inner region of the weld seam hasa thickness which preferably substantially corresponds to a thickness ofthe film for the case in which a film and a port are welded to oneanother. For the case in which two films are welded to one another, theweld seam has a thickness which preferably substantially corresponds toa total thickness of the two films.

In one embodiment, the neighboring region can also be provided by aperipheral outer region of the weld seam. The outer region of the weldseam describes the region which adjoins the exterior surroundings. Theperipheral outer region of the weld seam preferably has a thicknesswhich substantially corresponds to a thickness of the film or the totalthickness of the films.

The thickness of the film describes the film thickness with which thefilm was provided. The total thickness describes the total of the filmthicknesses of the two provided films, which are welded to one another.

The thickness of the weld seam preferably substantially corresponds tothe thickness of the film if it deviates by at most ±10%. The thicknessof the weld seam preferably substantially corresponds to the totalthickness of the two films if it deviates by at most ±10%.

This thinned-out region is formed in particular as the imprint of theabove-described elevation, for example, of the plateau described at theoutset.

In this region, the weld seam is reduced in the thickness because of thepressure produced by the elevation, for example, by the plateau.

The region which is thinned out or reduced in the thickness extends inparticular over a width of 30%-80%, preferably 60%-75%, of the width ofthe weld seam. The thinned-out region can extend, for example, in astrip shape along a region of the weld seam. It can in particular form astrip along a central, in particular a middle region of the weld seam.

The thickness of the film is preferably reduced in the region which isthinned out or reduced in thickness by at least 10%, preferably 10% to30%, in relation to the adjoining neighboring region.

The film is preferably 15% to 25% thinner in the thinned-out region thanin the adjoining region of the weld seam.

Furthermore, the weld seam can comprise a welded-in port. In particular,the weld seam can comprise a port having a ship-shaped welded-inportion, wherein at least one imprint of a rib, preferably two imprintsof two ribs, is/are provided in the region of the ship-shaped welded-inportion.

The weld seam is preferably between 1 and 10 mm, particularly preferablybetween 3 and 7 mm wide.

A sealing strip producing the weld stream is preferably between 5 and15, particularly preferably between 6 and 12 mm wide.

Moreover, a pharmaceutical product is also in the scope of theinvention. It comprises an embodiment of a medical pack formed as a bag,as described above. The bag is filled with a medical liquid, whichpreferably contains an active ingredient. A medical liquid is, forexample, a liquid to be administered intravenously. Examples of a liquidto be administered are a saline solution, a glucose solution, a nutrientsolution for parenteral feeding, an emulsion, or the like. The activeingredients can be provided in dissolved and/or dispersed form in theliquid.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is to be explained in greater detailhereafter with reference to an exemplary embodiment on the basis of FIG.1 to FIG. 17 of the drawings.

FIG. 1 is a schematic view of a medical pack according to the invention,which is formed as a bag.

FIG. 2 is a sectional view of the welding tool.

FIG. 3 is a detail view of FIG. 2.

FIG. 3a and FIG. 3b are detail views of FIG. 3, in which theconfiguration of the heating conductor and the boundary of the clampingregion are shown.

FIG. 4 is a perspective view of a welding jaw having applied bag andpartially removed upper part.

FIG. 5 is a perspective detail view of a welding jaw having completelyremoved upper part.

FIG. 6 is a perspective internal view of the upper part of a weldingjaw.

FIG. 7 is a perspective detail view of the region of a recess for theship-shaped welded-in portion of a port in a welding jaw.

FIG. 8 is a perspective illustration of the port region of a bag, whichwas produced using the welding tool shown in FIG. 7.

FIG. 9 shows an alternative embodiment of a welding jaw which is usedfor the weld seams, in which two films are bonded directly to oneanother (without ship-shaped welded-in portion of a port).

FIG. 9a is a detail view of the sealing strip of the welding jaw shownin FIG. 9.

FIG. 10 is a sectional view of the region of the sealing surface of thesealing strip shown in FIG. 9 a.

FIG. 11 is a schematic sectional view S_(F/F) of the region of a weldseam (see FIG. 1 in this regard) which was produced using the weldingtool shown in FIG. 9 and FIG. 10.

FIG. 12 is a detail view of the region of the recess for the ship-shapedwelded-in portion of a port according to a further embodiment of theinvention, in which the sealing surface has a plateau.

FIG. 13 is the section S_(P/F) of a weld seam in the region of theship-shaped welded-in portion of a port (see FIG. 1 in this regard),which was produced using the welding tool shown in FIG. 12.

FIG. 14 is a detail view of the port region of a bag, which was producedusing the welding tool shown in FIG. 12 and FIG. 13.

The steps of an exemplary embodiment of the method according to theinvention are to be explained with reference to the flowchart accordingto FIG. 15.

DETAILED DESCRIPTIONS OF THE DRAWINGS

FIG. 1 shows a medical pack formed as a bag 1, as can be producedaccording to the invention.

In this exemplary embodiment, the bag 1 comprises two ports 2, 3, inwhich one port 2 is provided for supplying and another port 3 isprovided for removing liquid. The invention can also relate to bags 1which comprise only one port 5 or a plurality of ports 5 (not shownhere). For example, a bag 1 can have one to four ports 5. The bags 1 canbe filled, for example, with a saline solution. Such bags 1 can inparticular also be prefilled with a solution already containing anactive ingredient.

The ports 2, 3 are welded in and each comprise one welded-in portion 5for this purpose. The examples shown here each show the welded-inportion 5 in the embodiment of a ship-shaped welded-in portion 5 (seealso FIGS. 4, 8, and 14 in this regard). The welded-in portions 5 canalso be provided in the form of a tube section or hose section.

The ship-shaped welded-in portions 5 are also welded into the bag edgeduring the welding of the weld seam 6, which is also referred to as atransverse weld seam, and are therefore covered by the film 9 of whichthe bag 1 consists.

The bag 1 consists, for example, of a polyolefin film, in particular ofa polyethylene or polypropylene film.

In addition to the transverse weld seam 6, the bag 1 is also closed bythe peripheral weld seams 7, which are also referred to as longitudinalweld seams, and by the upper transverse weld seam 8. In the region ofthe upper transverse weld seam 8, the bag 1 also comprises a hanger 4.

The cross section of a weld seam 6, 7, 8, in which two films 9 arewelded to one another directly (without welded-in port 5), is identifiedby S_(F/F). In contrast, the cross section of a weld seam 6 in which aport 5 is also welded into the film edge is identified by S_(P/F). Itwill be explained with reference to the following drawings how the weldseams 6, 7, 8 are formed.

FIG. 2 shows a schematic sectional view of parts of the welding tool, bymeans of which the films 9 and the port 5 are welded. In addition to thewelding jaws 10 a and 10 b, the welding tool also comprises themechanism (not shown here) for moving the welding jaws 10 a, 10 b, acoolant supply, and a control electronics unit, inter alia, foractivating the heating conductor 13.

To weld two films to one another, for example, the welding jaws 10 a and10 b are pressed onto the films 9 to form a weld seam 6. Each weldingjaw 10 a, 10 b comprises a cooling element 12 a and 12 b and an upperpart 11 a, 11 b. The cooling elements 12 a and 12 b protrude into therespective upper part 11 a and 11 b. Said upper parts 11 a and 11 b eachcomprise a sealing surface 17 and are pressed onto the films 9. The twoupper parts 11 a and 11 b, in particular the sealing surface 17 and/orthe clamping regions thereof, are preferably metallic and hard. They donot provide a flexible counter bearing. The two upper parts 11 a, 11 bare preferably constructed substantially symmetrically, in particularthe sealing surfaces 17 and clamping region thereof.

The lower part 28 a, 28 b of the respective welding jaw 10 a, 10 brespectively comprises a cooling channel 29 a, 29 b, which extends alongthe cooling element 12 a, 12 b and via which the cooling element 12 a,12 b is continuously cooled by conducting through coolant liquid. Theupper part 11 a/11 b is seated on the lower part 28 a/28 b and is cooledby the lower part 28 a/28 b.

FIG. 3 is a detail view of FIG. 2, in which it can be seen that aheating conductor 13 is arranged on each of the cooling elements 12 a,12 b. A membrane 15 is heated via the heating conductor 13 to plasticizethe plastic material of the films 9.

The welding procedure is carried out in pulsed operation. In this case,the cooling element 12 a, 12 b is continuously cooled using a liquid andthe heating conductor 13 is heated in a chronologically limited mannerin pulses.

If electric current flows through the heating conductor 13, the membrane15, which rests on the films 9, thus heats up to a temperature ofpreferably 180° C. to 350° C. and plasticizes the films 9 in the regionof the weld seam 6. The films 9 are plasticized or softened in such away that the films 9 bond to one another and/or the films 9 bond to theport 5 to form the weld seams 6, 7 and 8. The surface of the port 5 canpossibly also soften somewhat.

The boundaries 20 of the weld seam 6 illustrated here are indicated bythe dashed lines. The weld seam 6 is wider than the heating conductor13. The heating conductor 13 is preferably between 10 and 30%,particularly preferably between 15 and 25%, narrower than the weld seam6. The heating conductor 13 is preferably between 3 and 6 mm wide. Theclamping region 16 extends peripherally in relation to the boundary 20of the weld seam 6. The surface of the welding jaw 10, 10 a/10 b is setback peripherally in relation to the clamping region 16, since thesealing surface 17 and the clamping regions 16 are formed as a sealingstrip 32 protruding out of the surface of the welding jaw (see also FIG.9 and FIG. 9a in this regard).

The membrane 15 is preferably formed in one piece with the remainingupper part 11, 11 a, 11 b. The region of the membrane 15 comprises thesealing surface 17 of the respective welding jaw 10, 10 a, 10 b, 10 c.The membrane 15 preferably has a thickness of only 300-600 μm and isperipherally delimited by a solid block, which together form therespective upper part 11 a, 11 b. Due to its low thickness, the membrane15 can heat up rapidly upon switching on of the heating conductor 13 andafter the heating conductor 13 is switched off, can cool down againrapidly because of the permanent cooling. This enables a dynamic method.In particular, the adjoining clamping region 16 thus cannotsubstantially heat up (see also hereafter in the text in this regard).

The membrane 15 is tensioned upon heating and bulges slightly forward,i.e., in the direction of the film 9, because of the thermal expansion.A greater force per unit of area and thus an additional pressure isexerted on the weld seam 6 in this way. The plasticized material is thuscompressed, which improves the formfitting connection. This additionallyhas the result that possible shape and/or dimensional tolerances can becompensated for by material flowing into these regions because of theadditional pressure.

Because of the cooling, the clamping region 16 of the respective weldingjaw 10 a, 10 b adjoining the boundary 20 of the weld seam 6 issufficiently cold that the material is not plasticized in this region.

The welding jaws 10 a, 10 b thus rest on the films 9 and, because theyrest thereon, are held spaced apart using the adjoining clamping region16, in which the plastic material does not liquefy and therefore cannotbe displaced, in such a way that the plasticized material is not pressedout in the region of the weld seam 6. A closed cavity is thus formedinside the weld seam 6 during a welding procedure.

An insulating layer 14 is arranged between a heating conductor 13 and acooling element 12 a, 12 b. The heating conductors 13 are placed, forexample, with an insulating layer 14, in particular a silicone layer, onthe cooling elements 12 a, 12 b.

On the opposing side, the heating conductor 13 is applied directly tothe membrane 15 to ensure rapid heating of the membrane 15. At the sametime, the membrane 15 can only bulge forward, i.e., in the direction ofthe film 9, upon heating as a result of the applied heating conductor13. The heating conductor 13 and/or the membrane 15 are provided with athin insulating layer (not shown). This prevents the membrane 15 appliedto the heating conductor 13 from short-circuiting the heating conductor13. For this purpose, the side of the membrane 15 applied to the heatingconductor 13 can be provided, for example, with an insulating oxidelayer or a layer or film of polyimides (not shown).

The side walls of the cooling element 12, 12 a, 12 b are each spacedapart by a gap 35 from the opposing side wall of a recess of the upperpart 11 a, 11 b.

FIG. 3a is a detail view of the region A of FIG. 3. The heatingconductor 13 ends in this region. The heating conductor 13 is placed onthe cooling element 12/12 a here by means of an insulating layer 14, forexample, a silicone layer. The insulating layer 14 preferably producesan integrally-joined bond of the heating conductor 13 to the coolingelement 12/12 a. The insulating layer 14 acts as a thermal insulatinglayer. It can also act as an electric insulating layer, so that inparticular further electrical insulation of the cooling element 12/12 acan be omitted.

The cooling element 12/12 a is also continuously cooled during thewelding method. In particular because of the insulating layer 14, theheating conductor 13 operated in pulsed operation heats up sufficientlystrongly during a welding cycle that the membrane 15 is heated in theboundaries 20 of the weld seam 6 in such a way that the plastic materialof the adjoining film 9 plasticizes.

FIG. 3b is a detail view of the region B of FIG. 3. In the region inwhich the membrane 15 heats up in such a way that the plastic materialis plasticized, the membrane 15 forms the sealing surface 17. Thesealing surface 17 extends up to the boundary 20 of the weld seam 6. Themembrane 15 ends in a transition region 30, which is rounded here, andmerges into the upper part 11 a/11 b formed as a block 21. The clampingregion 16 adjoining the boundary 20 of the weld seam 6 beginsapproximately with the transition region 30 in this exemplaryembodiment.

The outer boundary 31 of the clamping region 16 is identified by a line.The sealing strip 32, which is formed from the sealing surface 17 andthe clamping region 16, protrudes out of the upper part 11 a/11 b inthis region.

FIG. 4 is a partially cutaway three-dimensional view of a welding jaw10, on which a bag 1 is laid. The bag 1 or the films 9 having the weldseam 6 to be formed are clamped by a welding tool for welding, inaccordance with the illustration according to FIG. 2. The second weldingjaw 10 of the welding tool is not shown here. The second welding jaw canbe embodied precisely like the welding jaw 10 visible here.

The upper part 11 of the welding jaw 10 and the bag 1 are blanked out onthe half shown on the left. The cooling element 12 protrudes into theupper part 11 and carries the heating conductor 13. The cooling element12 is cooled here using a liquid, in particular using water.

The welding jaw 10 shown here is designed to also weld in the port 2, 3in a welding procedure. For this purpose, the welding jaw 10 comprisesat least one recess 19, which is used to accommodate the ship-shapedwelded-in portion 5 of the port 2, 3. Furthermore, at least one holder18 is provided for securing the upper part of a port 2, 3. The heatingconductor 13 also follows the contour of the ship-shaped welded-inportion 5 in the region of the recess 19 for the ship-shaped welded-inportion 5.

The upper part 11 of the welding jaw 10 comprises the sealing strip 32.The sealing strip 32 provides the sealing surface 17 and the clampingregion 16. For this purpose, the sealing strip 32 protrudes out of theupper part 11. It represents a type of step in the upper side of theupper part 11. The lateral boundaries of the sealing strip 32 aredefined by the boundaries 31 of the clamping region 16 (see also FIG. 3bin this regard).

The sealing surface 17 heatable by the heating conductor 13 is providedin particular by the membrane 15.

During a welding procedure, the sealing surface 17 heats up, whereby theplastic material of the films 9 is plasticized.

For a welding procedure, the heating conductor 13 is heated for severalseconds, preferably for fewer than 3 seconds. In this case, the currentI (see also FIG. 5) flows through the heating conductor 13 formed as ametal strip, whereby the heating conductor 13 heats up, in spite of thecontinuous cooling via the cooling element 12/12 a/12 b.

The heating is then switched off and the material cools down rapidly, inparticular because of the cooling element 12. The cooling time untilopening the welding jaws 10 a, 10 b is preferably less than 3 seconds.

The clamping region 16 of the welding jaw 10 adjoining the sealingsurface 17 is used as a support on the film 9 of the bag 1 during thewelding procedure and is permanently cooled.

FIG. 5 is a perspective view of the welding jaw 10 with completelyremoved upper part 11.

The cooling element 12 comprises a main element or block 21 having thecoolant fittings 22, out of which the upper part of the cooling element12, which carries the heating conductor 13, protrudes. The recesses 19are each used to accommodate one ship-shaped welded-in portion 5 of aport 2, 3. The upper parts of a port 2, 3 are supported by the holders18.

The cooling element 12 preferably consists of a material having goodthermal conductivity, in particular of aluminum or copper or an aluminumor copper alloy.

The heating conductor 13 can be a copper strip. However, the heatingconductor 13 can also be, for example, a metal strip of an iron-nickelalloy, preferably having a coefficient of thermal longitudinal expansionα less than 5*10⁻⁶/K, particularly preferably less than 2*10⁻⁶/K (at 20°C. to 300° C.)

FIG. 6 is a perspective internal view of the upper part 11 of a weldingjaw 10. In particular the membrane 15, the opposing side of which formsthe sealing surface 17, can be seen in this illustration. The upper part11 has a trench, into which the cooling element 12 protrudes (see alsoFIG. 5 in this regard). The upper part 11 is formed here as a solidblock, in which the membrane 15 is tensioned. The upper part 11 and themembrane 15 are preferably embodied in one piece.

The upper part 11 preferably consists of a metal having low thermalexpansion, in particular of an iron-nickel alloy. The coefficient ofthermal longitudinal expansion α of the material is less than 5*10⁻⁶/K,particularly preferably less than 2*10⁻⁶/K at 20° C. to 300° C. in onepreferred embodiment of the invention.

FIG. 7 is a perspective detail view of the region of the upper part 11a, 11 b, in which a recess 19 is provided for the ship-shaped welded-inportion 5 of a port 2, 3. The recess 19 is formed as a trench-shapeddepression extending transversely in relation to the sealing strip 32,through which the sealing surface 17 extends, to weld the film 9 to theship-shaped welded-in portion of a port 2, 3.

The sealing strip 32 or the sealing surface 17 is also shown withoutplateau 23 here. Two ribs 24 spaced apart from one another protrude outof the sealing surface 17 into the recess 19. The ribs 24 endessentially in the region in which the recess 19 merges back into aplane, which the sealing surface 17 forms in the region in which twofilms 9 are welded to one another. The ribs 24 preferably have a widthof 0.5 to 1.5 mm and/or a height of 10-60 μm.

The pressing of the film 9 onto the ship-shaped welded-in portion 5 canbe improved by the ribs 24. Furthermore, material is displaced by theribs 24, so that manufacturing tolerances of the ports 2, 3 or the film9 can be compensated for.

The sealing surface 17, the boundaries 20 of the weld seam 9 to beproduced, and the clamping region 16 and its boundaries 31 are onlyillustrated here in the plane of the sealing surface 32. The listedfeatures are not shown in the recess 19 for reasons of illustration.

FIG. 8 is a detail view of the bag 1 in the region of a port 2, 3, ofwhich the ship-shaped welded-in portion 5 is shown here. In thisembodiment of a bag 1, the port 2, 3 was welded in using the toolillustrated above in FIG. 7. The weld seam 6 is illustrated, whichextends both over the region in which two films 9 are located one on topof another and also over the ship-shaped welded-in portion 5.

Two imprints 27 are provided in the region of the ship-shaped welded-inportion 5. These essentially correspond to the ribs 24 of the sealingstrip 32 and/or the sealing surface 17. The two imprints 27 extendessentially parallel to the weld seam 6 here and end in the region ofthe two ends of the ship-shaped welded-in portion 5, which taper to apoint. The region of the weld seam 6 adjoining thereon only consists ofthe films 9 welded on one another.

FIG. 9 shows a perspective view of a further embodiment of a welding jaw10 c, which does not have recesses 19 for accommodating a ship-shapedwelded-in portion 5 of a port 2, 3.

The welding jaw 10 c shown here thus comprises a sealing strip 32without recesses 19 and is used in particular to form the weld seams 7and 8 shown in FIG. 1. The fundamental structure of this welding jaw 10c essentially corresponds to the structure of the above-describedwelding jaws 10, 10 a, and 10 b. The sealing strip 32 protrudes out ofthe upper part 11 of the welding jaw, which is formed here in particularas a block.

FIG. 9a is a detail view of the region A of FIG. 9, which shows thesealing strip 32.

The sealing strip 32 is delimited by the boundaries 31 of the clampingregions 16. The boundaries 20 of the weld seam 6 define the extension ofthe sealing surface 17 (see also FIGS. 3, 3 a, and 3 b in this regard).

A plateau 23, the configuration and function of which will be describedhereafter, also additionally extends above the sealing strip 32 insidethe sealing surface 17 illustrated here.

FIG. 10 is a sectional view along the dashed line shown in FIG. 9a inthe region B of the sealing strip 32. The section is executed in a planeperpendicular to the main extension direction of the sealing strip 32.

The cross section of an upper side section of the sealing strip 32and/or the membrane 15 over which the sealing surface 17 extends isshown. The two outer boundaries 31 of the clamping regions 16 are notshown here.

In this exemplary embodiment, the sealing surface 17 and/or the membrane15 in the region of the sealing surface 17 is not formed completelylevel over the entire width, but rather additionally comprises theplateau 23.

The boundaries 20 of the weld seam 6, by which the edge of the sealingsurface 17 is also defined, extend so that the plateau 23 is locatedinside the weld seam 6. Adjoining the plateau 23, the sealing surface 17also comprises the regions 33 i and 33 e.

The mentioned region 33 i is the peripheral inner region of the sealingsurface 17. This is the region 33 i of the sealing surface 17 whichproduces or provides the inner region 25 i of the weld seam 6, 7, 8.This is the region 25 i of the weld seam 6, 7, 8 which adjoins theinterior of the bag 1.

The region 33 e, in contrast, is the peripheral outer region of thesealing surface 17. This is the region 33 e of the sealing surface 17which provides the outer (external) region 25 e of the weld seam 6, 7,8. This is the region 25 e of the weld seam 3, 7, 8 which adjoins theexterior of the bag 1.

The peripheral inner region 33 i of the sealing surface 17 and theperipheral outer region 33 e of the sealing surface 17 are at a heightor essentially at a height with the respective adjoining clamping region16.

The plateau 23 is embodied in particular as a plate-shaped plane in thisexemplary embodiment.

The plateau 23 extends like a web or a strip, preferably substantiallycentrally, along the main extension direction of the sealing surface 17.

The plateau 23 protrudes beyond the adjoining clamping region 16 of thesealing strip 32. It is embodied as a type of step in the upper side ofthe sealing strip 32, the sealing surface 17, and/or the membrane 15.

An additional pressure is thus exerted on the film 9 in the region ofthe plateau 23 during the welding procedure. The pressure per unit ofarea is thus greater because of the plateau 23 in this region of thesealing surface 17 than in the adjoining outer region 33 of the sealingsurface 17.

The plateau 32 is narrower than the total width of the sealing surface17. The plateau is preferably also narrower than the heating conductor13, in particular narrower by 0.2 to 0.8 mm. The boundaries 34 of theheating conductor 13 (not shown here) are marked by a dashed line. Theheating conductor 13 itself is narrower than the weld seam 6, since themembrane 15 also heats up laterally adjoining the heating conductor 13sufficiently strongly that the material of the film 9 is plasticized upto the boundary 20 of the weld seam 6.

The sealing strip 32 delimited by the outer boundary 31 of the clampingregions 16 is preferably between 5 and 15 mm, particularly preferablybetween 6 and 12 mm wide.

On the one hand, the film 9 is pressed on more strongly in the region ofthe weld seam 7 by the plateau 23. On the other hand, the melted, moltenplastic material can flow into possible cavities, which can be presentbecause of shape and/or dimensional tolerances, since it is displaced asa result of the higher pressure (see also FIG. 12 in this regard).

In one preferred embodiment, the plateau 23 has a height of less than100 μm, preferably less than 60 μm. The risk thus does not exist thatlarger quantities of molten plastic will be pressed into the adjoiningclamping region 16. The adjoining cooled clamping region 16 is closed inany case because of the applied film 9.

Because the membrane 15 as a whole is very thin, it is elastic and canin turn again yield to a pressure in the volume, which is formed by themolten plastic.

FIG. 11 shows the sectional view of a weld seam 7 of a bag 1, which wasproduced using the welding tool illustrated in FIGS. 9, 9 a, and 10, inthe region in which two films 9 are welded to one another (see thesection S_(F/F) in FIG. 1 in this regard). On the side shown on the lefthere, the weld seam 7 adjoins the enclosed interior of the bag 1. On theside shown on the right here, the weld seam 7 adjoins the external roomor the surroundings of the bag 1. The two films 9 are not welded to oneanother on the left and right of the boundaries 20 of the weld seam 7.

The contour or the profile of the weld seam 7 is an imprint of thecontour or the profile of the sealing surface 17 shown in FIG. 10.

A thinned-out region 26, on which non-thinned-out neighboring regions 25adjoin, is provided in the middle part of the weld seam 7. Thethinned-out region 26 represents the imprint of the plateau 23. The weldseam region 25 i (shown on the left here) adjoining the interior of thebag 1 and the weld seam region 25 e (shown on the right here) adjoiningthe (external) surroundings of the bag 1 have a greater thickness thanthe thinned-out region 25. The peripheral inner region 25 i of the weldseam 7 in particular has a thickness which essentially corresponds tothe total thickness of the two films 9. The greater thickness of theweld seam 7 in the region 25 i adjoining the interior has proven to beextremely advantageous for the stability of the weld seam 9. Theperipheral outer region 25 e of the weld seam 7 can also have athickness, as shown here, which essentially corresponds to the totalthickness of the two films 9.

FIG. 12 shows a perspective view of a further exemplary embodiment, inwhich the region of the sealing surface 17 is shown in the region of therecess 19 for a ship-shaped welded-in portion 5 corresponding to theillustration according to FIG. 7. The sealing surface 17, its boundaries20, and the clamping region 16 and its boundaries 31 are only partiallyillustrated here.

In this embodiment of the invention, the sealing surface 17 comprisesthe plateau 23, corresponding to the embodiment shown in FIG. 10, whichextends over both the region of the recess 19 and also over theremaining level sealing surface 17 or sealing strip 32. In addition, tworibs 24 are applied to the plateau 23 (see also FIG. 7 in this regard).

FIG. 13 is a schematic sectional view of a film 9, which was processedin a welding method, in which the welding tool shown in FIG. 12 was used(see section S_(P/F) in FIG. 1 in this regard). The weld seam 6 is shownin the region of the ship-shaped welded-in portion 5 (only schematicallyindicated). On the side shown on the right here, the weld seam 6 adjoinsthe enclosed interior of the bag 1. On the side shown on the left here,the weld seam 7 adjoins the external room or the surroundings of the bag1.

The weld seam 6 has a thinned-out region 26, which is provided becauseof the imprint of the plateau 23, inside its boundaries 20.

The thinned-out region 26 is located centrally, preferably approximatelyin the middle, in the weld seam 6. A neighboring region 25 or 25 i and25 e, in which the film 9 is essentially not thinned out, is provided ineach case adjoining the thinned-out region 26. The film 9 is also weldedor bonded to the port 2, 3 or its ship-shaped welded-in portion 5 inthis region 25. In the region 25, however, the film 9 has essentiallythe same thickness as in the adjoining region, in which the film 9 isnot welded to the ship-shaped welded-in portion 5. The greater thicknessin the inner peripheral region 25 i of the weld seam 6 has proven to beadvantageous for the stability of the weld seam 6 as a whole in thiscase.

Furthermore, two imprints 27, which were introduced by the ribs 24, arealso present inside the thinned-out region 26.

In contrast, the weld seam 6 corresponds to the illustration in FIG. 11outside the region shown of the ship-shaped welded-in portion 5.

FIG. 14 is a detail view of the bag 1 in the region of a port 2, 3, ofwhich the ship-shaped welded-in portion 5 is shown. In this embodimentof a bag 1, the port 2, 3 was welded into the bag 1 using the tool shownabove in FIG. 12. The weld seam 6 is illustrated here, which extendsover the region in which two films 9 are bonded, and over the region inwhich the films 9 are bonded to the port 2, 3 or to its ship-shapedwelded-in portion 5. The thinned-out region 26 and the twonon-thinned-out peripheral inner regions 25 i and outer regions 25 e inthe weld seam 6, which extend over the entire length of the weld seam 6,can be seen. This thinned-out region 26 in the weld seam 6 is theimprint of the above-described plateau 23. Moreover, two imprints 27 areprovided in the region of the ship-shaped welded-in portion 5. Theseessentially correspond to the ribs 24 of the sealing strip 32 or thesealing surface 17 (see the description of FIG. 8 in this regard).

FIG. 15 is a flowchart of the method steps of an exemplary embodiment ofa welding method according to the invention.

The welding method is executed as a noncontinuous pulse method, inparticular having permanent cooling.

Firstly the film 9 is fed between the welding jaws 10, 10 a, 10 b, 10 cof the welding tool.

The two welding jaws 10, 10 a, 10 b, 10 c are then pressed together orclosed. The closed state is firstly defined by the stop of the plateaus23. The plateaus are used as a type of spacer. In this state, theclamping regions 16 of the upper and the lower welding jaw 10, 10 a, 10b, 10 c preferably do not yet come to the stop.

The respective heating conductor 13 is heated. The sealing surfaces 17are heated by the heating conductor 13. The heating is in such a waythat the films 9 are plasticized in the region of the sealing surfaces17. The plateaus 23 can plunge into the now free-flowing film material.The welding jaws 10, 10 a, 10 b, 10 c thus close completely. Theclamping regions 16 now press against one another, separated by thefilms 9. The clamping regions 16 are cool or are cooled in such a waythat the films 9 are not plasticized there. A closed space is thusformed.

Liquid film material is intentionally displaced by the plunging of theplateaus 23 into the plasticized films 9. The film material is inparticular displaced at least laterally along the weld seam 6, 7, 8. Thedisplaced film material can compensate for possible shape and/ordimensional tolerances in the films 9 and/or the ports 5 or fill themup. In the inner peripheral region 25 i of the weld seam 6, 7, 8, incontrast, the film thickness is maintained.

The membrane 15 of the welding jaws 10, 10 a, 10 b, 10 c can bulge andexert additional pressure on the weld seam 6, 7, 8. According to anotherembodiment of the invention, the heating conductor 13 can also alreadybe heated before the welding jaws 10, 10 a, 10 b, 10 c are pressedtogether.

The power supply to the heating conductor 13 is then switched off andthe weld seam 6 cools down, inter alia, because of the preferablycontinuously running coolant supply, so that the welding tool can beopened when the material of the films 9 has sufficiently solidifiedagain.

Considered as a whole, the method according to the invention can becompared to a combination of seam welding and injection molding. This isbecause a closed region, in which the material is molten during thewelding procedure, is formed by the clamping of the film 9. It ispossible to intentionally change the contour of the weld seam 9 in thiscase via an adaptation of the contour of the sealing surface 17 of thewelding jaw in this region.

The susceptibility of a pulse welding method for welding plastic filmsto shape and dimensional tolerances, in particular to shape anddimensional tolerances of a port to be welded in, could be significantlyreduced by the invention.

LIST OF REFERENCE SIGNS

1 bag

2 port

3 port

4 hanger

5 welded-in portion or ship-shaped welded-in portion

6 weld seam (transverse weld seam)

7 weld seam (longitudinal weld seam)

8 weld seam (transverse weld seam having hanger)

9 film

10, 10 a, 10 b, 10 c welding jaw

11, 11 a, 11 b upper part

12, 12 a, 12 b cooling element

13 heating conductor

14 insulating layer

15 membrane

16 clamping region

17 sealing surface

18 holder

19 recess

20 boundary of the weld seam

21 block

22 coolant fitting

23 plateau

24 rib

25 neighboring region to the thinned-out region

25 i peripheral inner region of the weld seam (adjoining the interior ofthe bag)

25 e peripheral outer region of the weld seam (adjoining the externalsurroundings of the bag)

26 region in the weld seam which is reduced in thickness or thinned out

27 imprint of the rib in the weld seam

28 a, 28 b lower part

29 a, 29 b cooling channel

30 transition region (of the membrane)

31 boundary of the clamping region

32 sealing strip

33 outer region of the sealing surface

33 i peripheral inner region of the sealing surface

33 e peripheral outer region of the sealing surface

34 boundary of the heating conductor

35 gap between cooling element and upper part

1. A welding tool for pulse welding a film made of plastic of a packwhich is preferably medical, comprising a welding jaw having a sealingstrip, which extends along the welding jaw and can be pressed onto thefilm, wherein the sealing strip comprises a heatable sealing surface forforming a weld seam to plasticize plastic material of the film adjoiningthe sealing surface, and peripherally in relation to the sealing surfacehas an adjoining inner clamping region and preferably an adjoining outerclamping region for clamping the film during welding of the film,wherein the sealing surface has an elevation for displacing plasticizedplastic material of the film.
 2. The welding tool as claimed in claim 1,wherein the elevation is provided by a plateau which protrudes out of asurface of the sealing surface.
 3. The welding tool as claimed in claim1, wherein a peripheral inner region of the sealing surface is arrangeddepressed in relation to the elevation.
 4. The welding tool as claimedin claim 1, wherein the elevation is arranged essentially in the middlein the sealing surface.
 5. The welding tool as claimed in claim 1,wherein the inner clamping region and/or the outer clamping regionis/are provided during the welding with a temperature which is less thanthe plasticizing temperature of the film to be welded.
 6. The weldingtool as claimed in claim 1, wherein, the peripheral inner region of thesealing surface and/or the peripheral outer region of the sealingsurface is or are essentially at one height with the respectiveadjoining clamping region.
 7. The welding tool as claimed in claim 1,comprising a cooling element, on which an electrical heating conductoris placed, wherein an upper part having the sealing strip is placed onthe cooling element and/or a bulging membrane, wherein the membranecomprises the sealing surface.
 8. The welding tool as claimed in claim1, wherein the upper part of the welding tool has at least one recess,which is designed to accommodate a welded-in portion of a port.
 9. Thewelding tool as claimed in claim 1, wherein the sealing surfacecomprises at least one protruding rib, preferably two protruding ribs,in the region of the port to be welded in, in particular in the regionof the welded-in portion of a port.
 10. The welding tool as claimed inclaim 1, wherein the welding tool is designed in such a way that thesealing surface is heatable more strongly in the region of the recessfor the welded-in portion than in an adjoining region of the sealingsurface, in which two films are welded to one another.
 11. The weldingtool as claimed in claim 1, wherein the plateau is provided as astrip-shaped contour on the sealing surface and/or the plateau occupies30 to 80%, preferably 60 to 75%, of the width of the weld seam and/orthe plateau is provided having a height between 10 and 100 μm,preferably between 20 and 60 μm.
 12. A use of a welding tool as claimedin claim 1 for producing a medical pack formed as a bag.
 13. A pulsewelding method using a welding tool for pulse welding a film made ofplastic of a pack, which is preferably medical, in particular as claimedin claim 1, wherein a welding jaw of the welding tool is pressed with aheatable sealing surface to form a weld seam onto the film in such a waythat a cavity is formed in the welding tool during the welding, by thefilm being clamped peripherally in relation to the sealing surfaceduring the welding procedure by a clamping region, which is cooler thanthe sealing surface and extends peripherally in respect to the sealingsurface and plasticized plastic material of the film is displaced by anelevation of the sealing strip, preferably at least laterally, along theweld seam to compensate for shape and/or dimensional tolerances, whereinthe film thickness is essentially maintained in a peripheral innerregion of the weld seam.
 14. The method as claimed in claim 13, whereina force is exerted on the film both by the sealing surface and also bythe clamping region extending peripherally in respect to the sealingsurface by a surface pressure and/or upon heating of the sealingsurface, a higher surface pressure is exerted in the region of thesealing surface than in the clamping region.
 15. The method as claimedin claim 1, wherein the plasticized plastic material is displaced by theelevation of the sealing strip in a peripheral inner region of the weldseam and in particular in a peripheral outer region of the weld seam.16. The method as claimed in claim 1, wherein the elevation of thesealing surface is provided by an elevation, preferably by a plateau,which protrudes out of a surface of the sealing surface, and/or theelevation of the sealing surface is provided by a bulging membrane,wherein the membrane comprises the sealing surface.
 17. A medical packformed as a bag, which comprises films welded to one another, inparticular producible using a method and/or using a welding tool asclaimed in claim 1, wherein the bag comprises at least one weld seamwhich has at least in sections a region reduced in the thickness inrelation to an adjoining neighboring region of the weld seam, whereinthe neighboring region is provided by a peripheral inner region of theweld seam and the peripheral inner region of the weld seam has athickness which essentially corresponds to a thickness of the film or atotal thickness of the films.
 18. The medical pack formed as a bag asclaimed in claim 17, wherein the neighboring region is provided by aperipheral outer region of the weld seam and the peripheral outer regionof the weld seam in particular has a thickness which essentiallycorresponds to a thickness of the film or a total thickness of thefilms.
 19. The medical pack formed as a bag as claimed in claim 1,wherein the region reduced in the thickness extends in a strip shapealong a region of the weld seam.
 20. The medical pack formed as a bag asclaimed in claim 1, wherein the thickness of the film is reduced in theregion reduced in the thickness in relation to the adjoining neighboringregion by at least 10%, preferably by 10 to 30%, and/or the regionreduced in the thickness occupies 30% to 80%, preferably 60% to 75%, ofthe width of the weld seam.
 21. The medical pack formed as a bag asclaimed in claim 1, wherein by a port welded into the weld seam via awelded-in portion, in particular wherein at least one imprint of a rib,preferably two imprints of two ribs, are provided in the film in theregion of the welded-in portion of the port.
 22. A pharmaceuticalproduct comprising a medical pack formed as a bag as claimed in claim 1,wherein the bag is filled with a medical liquid, preferably containingan active ingredient.